Functions of small proteins regulated during Salmonella infection
University of Würzburg (Germany), Institute for Molecular Infection Biology (IMIB)
The Gram-negative bacterium Salmonella Typhimurium is a facultative intracellular pathogen causing gastrointestinal infections. The extensive knowledge from Salmonella as a model for studying the functions of proteins and non-coding RNAs in infection makes this organism a promising model for understanding how small proteins contribute to bacterial virulence.
YjiS is an uncharacterized, 54 aa-long protein that contains an arginine-rich domain of unknown function (DUF1127). The yjiS gene is highly induced in Salmonella grown in infection-relevant conditions. Several TraDIS (transposon-directed insertion sequencing) datasets predict that YjiS affects the outcome of infection when targeted by a transposon, both in vitro and in vivo (Barquist, unpublished; Barquist et al., 2013; Chaudhury et al., 2013). This was confirmed by in vitro infection assays using a Salmonella ΔyjiS strain: at 22 hours post-infection, there were 1.6-fold more bacteria in the host cells, as compared to infection with the wild-type strain. Furthermore, RNA-seq data suggest that YjiS acts as a repressor for flagella and motility-related genes.
We will further characterize the role of this small protein by applying state-of-the-art techniques such as dual RNA-seq (Westermann et al., 2016), which allows to chart the transcriptome of both host and pathogen at different stages of infection. In particular, we will perform differential dual RNA-seq, comparing datasets from infection of HeLa cells with wild-type Salmonella and the ΔyjiS mutant. This, together with standard biochemical approaches to investigate the molecular mechanism at the basis of its activity, will shed light on how YjiS participates to the complex process of infection.
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